Field of the Invention
The invention generally relates to an electronic apparatus, and more particularly, to an electronic apparatus having anti-ghosting (N-key rollover) capability and a detection method of status of keys thereof.
Description of Related Art
With reference to FIG. 1, FIG. 1 illustrates a conventional keyboard apparatus 100. The keyboard apparatus 100 may include keys SW1-SW4 and comparators 10, 20. The key SW1 is coupled between a driving line DL1 and a sensing line SL1. The key SW2 is coupled between the driving line DL1 and a sensing line SL2. The key SW3 is coupled between a driving line DL2 and the sensing line SL1. The key SW4 is coupled between the driving line DL2 and the sensing line SL2. The comparator 10 is coupled to the sensing line SL1 to receive a voltage signal SV1 and compares the voltage signal SV1 with a reference voltage Vref. Similarly, the comparator 20 is coupled to the sensing line SL2 to receive a voltage signal SV2 and compares the voltage signal SV2 with the reference voltage Vref.
During a process of detecting a press status of the keys SW1-SW4, the driving line DL1 is driven to a voltage potential and the driving line DL2 is driven to another voltage potential. When the driving line DL1 is driven to the voltage potential, the keys SW1 and SW2 may respectively transmit the corresponding voltage signals SV1, SV2 to the comparators 10, 20 through the sensing lines SL1, SL2 according to the press status of the keys SW1, SW2. Then, the voltage signals SV1, SV2 are respectively compared to the reference voltage Vref by the comparators 10, 20 to determine the press status of the keys SW1, SW2. Similarly, the driving line DL2 is driven to a voltage potential and the driving line DL1 is driven to another voltage potential. When the driving line DL2 is driven to the voltage potential, the keys SW3 and SW4 may respectively transmit the voltage signals SV1, SV2 to the comparators 10, 20 through the sensing lines SL1, SL2 according the press status of the keys SW3 and SW4. Then, the voltage signals SV1, SV2 are respectively compared to the reference voltage Vref by the comparators 10, 20 to determine the press status of the keys SW3 and SW4.
It should be noted that as the number of the keys in the keyboard apparatus increases, the number of the sensing lines would increases, which causes the number of the comparators coupled to the sensing lines for comparing the voltages to increase as well. However, the comparators may have different tolerances due to the drift occurred during the manufacturing fabrication, which may cause misjudgment on the press status of the keys. Therefore, calibrations are performed on each of the comparators to obtain an offset corresponding to each of the comparators, so as to accurately detect the press status of the corresponding keys. Since the process of detecting the status of the keys must store the offset of each of the comparators, such would consume more circuitry resources.